Inspection devices of a dual energy type have been known which irradiate subjects to be inspected such as foods and industrial products with radiations such as X-rays and detect the radiations transmitted through the subjects in different ranges such as low and high energy ranges, so as to perform nondestructive inspections. Such a nondestructive inspection device can acquire radiation images in low and high energy ranges at the same time.
Carrying out predetermined operations (such as division, subtraction, addition, and multiplication) between the radiation images acquired in the different energy ranges makes it possible to highly accurately determine distributions of components intricately mixing together, detect foreign matters which are hard to get a contrast, and so forth. For acquiring radiation images in different energy ranges, such an inspection device is equipped with detectors corresponding to the respective energy ranges and employs a structure in which the detectors are arranged in a vertical row (see FIG. 9 of Patent Literature 1), for example.